Re: Raid5 to another raid level??

[Michael Busby <michael.a.busby@gmail.com>]

As could not sleep, have just tested and works fine...here is what i have done

sdd and sde are the 2 new disks

mdadm -C /dev/md1 -l4 -n3 -e 1.0 /dev/sdd /dev/sde missing

not sure if worth now using 1.2 as this seems the default setting if
not specified??

sdb and sdc are the old raid 5 disks

echo frozen > /sys/block/md0/md/sync_action
mdadm /dev/md0 --add /dev/sdb
mdadm --grow --force /dev/md0 --raid-disks=4

echo frozen > /sys/block/md0/md/sync_action
mdadm /dev/md0 --add /dev/sdc
mdadm --grow --force /dev/md0 --raid-disks=5

echo raid0 > /sys/block/md0/md/level

then resize the fs...job done :)



On 2 September 2011 00:50, Michael Busby <michael.a.busby@gmail.com> wrote:
> Will test tomorrow once back in the office, hope the 4tb sync will be
> finished by then
>
> I will report back my findings
>
>
>
> -- Sent from my HP TouchPadOn 1 Sep 2011 11:34 PM,
> <john.robinson@anonymous.org.uk> wrote:
> On 01/09/2011 22:50, Michael Busby wrote:
>> I have found the following and see that you can convert from raid4 to
>> raid0 fairly easy
>>
>>
>> http://ubuntuforums.org/showpost.php?p=10412231&postcount=20
>>
>> i have a 2 disk raid5 and want to be able to convert this to raid0, i
>> was thinking of adding a extra 2 disk and setting them up as raid0,
>> moving the data over then adding the original raid5 disks to the raid0
>> setup, but i see that you are unable to add disk to a raid0 setup,
>> would it be possible to setup a raid4 with 2 disks and 1 missing, move
>> the data from the raid5 to raid4 then add both of the original disks
>> to the raid4 the downgrade this to raid0???
>
> Off the top of my head, feeling slightly sozzled (been for a few beers),
> this might work, but as your linked post referring to a list reply from
> Neil Brown says, you should test first. You could use some USB sticks,
> or alternatively loopback devices are ideal for this kind of test.
>
> Cheers,
>
> John.
>